Allow enabling sqrt optimizations while computing

src/FactorizationController.cpp

@@ -58,7 +58,17 @@ void FactorizationController::setUseSqrtOptimization(bool value) {
 
     m_useSqrtOptimization = value;
     emit useSqrtOptimizationChanged();
-    reset();
+
+    // We're in a reset state
+    if (m_originalNumber == 0)
+        return;
+
+    if (m_useSqrtOptimization)
+        m_stopFactor = static_cast<unsigned long long>(std::sqrt(m_currentFactNumber));
+    else
+        m_stopFactor = m_currentFactNumber - 1;
+    emit stopFactorChanged();
+    emit progressChanged();
 }
 
 bool FactorizationController::pauseOnFound() const {

src/FactorizationController.h

@@ -167,8 +167,10 @@ class FactorizationController : public QObject {
      * Generally, there's no reason to disable this optimization, however, if you wish to
      * perform a slower search, it is a way to achieve that.
      *
-     * Note that changing this value while the computation is in progress will reset the
-     * computation.
+     * This value can be changed even as a computation is ongoing; if you do so, the stop factor
+     * will change immediately, which will very likely cause the progress bar to rapidly change.
+     * It is possible that after enabling, the computation will immediately finish, as the stop
+     * factor will be less than the sqrt(x).
      */
     void setUseSqrtOptimization(bool value);